================================================================== BUG: KASAN: use-after-free in tcp_ack_probe net/ipv4/tcp_input.c:3292 [inline] BUG: KASAN: use-after-free in tcp_ack+0x414f/0x4760 net/ipv4/tcp_input.c:3714 Read of size 4 at addr ffff88809491b06c by task syz-executor.1/7447 9pnet: p9_fd_create_tcp (7481): problem connecting socket to 127.0.0.1 CPU: 0 PID: 7447 Comm: syz-executor.1 Not tainted 4.14.143 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x138/0x197 lib/dump_stack.c:53 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 tcp_ack_probe net/ipv4/tcp_input.c:3292 [inline] tcp_ack+0x414f/0x4760 net/ipv4/tcp_input.c:3714 tcp_rcv_established+0x3e9/0x1650 net/ipv4/tcp_input.c:5555 tcp_v6_do_rcv+0x417/0x1190 net/ipv6/tcp_ipv6.c:1301 tcp_v6_rcv+0x2446/0x2ed0 net/ipv6/tcp_ipv6.c:1519 ip6_input_finish+0x300/0x15a0 net/ipv6/ip6_input.c:284 NF_HOOK include/linux/netfilter.h:250 [inline] NF_HOOK include/linux/netfilter.h:244 [inline] ip6_input+0xd5/0x340 net/ipv6/ip6_input.c:327 dst_input include/net/dst.h:468 [inline] ip6_rcv_finish+0x23f/0x7a0 net/ipv6/ip6_input.c:71 NF_HOOK include/linux/netfilter.h:250 [inline] NF_HOOK include/linux/netfilter.h:244 [inline] ipv6_rcv+0xe4d/0x1d20 net/ipv6/ip6_input.c:208 __netif_receive_skb_core+0x1eae/0x2ca0 net/core/dev.c:4477 __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4515 process_backlog+0x21f/0x730 net/core/dev.c:5197 napi_poll net/core/dev.c:5598 [inline] net_rx_action+0x490/0xf80 net/core/dev.c:5664 __do_softirq+0x244/0x9a0 kernel/softirq.c:288 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1015 do_softirq.part.0+0x10e/0x160 kernel/softirq.c:332 do_softirq kernel/softirq.c:324 [inline] __local_bh_enable_ip+0x154/0x1a0 kernel/softirq.c:185 local_bh_enable include/linux/bottom_half.h:32 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:725 [inline] ip6_finish_output2+0x9f3/0x21b0 net/ipv6/ip6_output.c:121 ip6_finish_output+0x4f4/0xb50 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip6_output+0x20f/0x6d0 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:462 [inline] NF_HOOK include/linux/netfilter.h:250 [inline] NF_HOOK include/linux/netfilter.h:244 [inline] ip6_xmit+0xd53/0x1eb0 net/ipv6/ip6_output.c:275 inet6_csk_xmit+0x286/0x4d0 net/ipv6/inet6_connection_sock.c:139 __tcp_transmit_skb+0x172c/0x2fe0 net/ipv4/tcp_output.c:1130 tcp_transmit_skb net/ipv4/tcp_output.c:1146 [inline] tcp_write_xmit+0x523/0x4960 net/ipv4/tcp_output.c:2382 tcp_push_one+0xc1/0xf0 net/ipv4/tcp_output.c:2577 tcp_sendmsg_locked+0x157c/0x3200 net/ipv4/tcp.c:1406 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xce/0x110 net/socket.c:656 SYSC_sendto+0x206/0x310 net/socket.c:1763 SyS_sendto+0x40/0x50 net/socket.c:1731 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4598e9 RSP: 002b:00007f0965fb1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00000000004598e9 RDX: 00000000fffffdda RSI: 00000000200000c0 RDI: 000000000000000a RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0965fb26d4 R13: 00000000004c7880 R14: 00000000004dd188 R15: 00000000ffffffff Allocated by task 7444: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3642 __alloc_skb+0x9c/0x500 net/core/skbuff.c:193 alloc_skb_fclone include/linux/skbuff.h:1022 [inline] sk_stream_alloc_skb+0xb3/0x780 net/ipv4/tcp.c:855 tcp_sendmsg_locked+0xf61/0x3200 net/ipv4/tcp.c:1301 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xce/0x110 net/socket.c:656 SYSC_sendto+0x206/0x310 net/socket.c:1763 SyS_sendto+0x40/0x50 net/socket.c:1731 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 7444: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kmem_cache_free+0x83/0x2b0 mm/slab.c:3758 kfree_skbmem+0x8d/0x120 net/core/skbuff.c:607 __kfree_skb+0x1e/0x30 net/core/skbuff.c:646 sk_wmem_free_skb include/net/sock.h:1416 [inline] tcp_remove_empty_skb.part.0+0x231/0x2e0 net/ipv4/tcp.c:929 tcp_remove_empty_skb net/ipv4/tcp.c:925 [inline] tcp_sendmsg_locked+0x1ced/0x3200 net/ipv4/tcp.c:1435 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xce/0x110 net/socket.c:656 SYSC_sendto+0x206/0x310 net/socket.c:1763 SyS_sendto+0x40/0x50 net/socket.c:1731 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 The buggy address belongs to the object at ffff88809491b040 which belongs to the cache skbuff_fclone_cache of size 472 The buggy address is located 44 bytes inside of 472-byte region [ffff88809491b040, ffff88809491b218) The buggy address belongs to the page: page:ffffea00025246c0 count:1 mapcount:0 mapping:ffff88809491b040 index:0x0 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffff88809491b040 0000000000000000 0000000100000006 raw: ffffea00025a6b20 ffffea0002a03ee0 ffff8880a9e19a80 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809491af00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc ffff88809491af80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88809491b000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff88809491b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809491b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================